At this stage, I've learned all the necessary letters to answer the questions that they asked so far. I do understand that some of the letters take on a different form depending on it's location in the word. I believe I learned that in an outside source. With that being said, don't depend on just Duolingo. I will say this though, I haven't been asked to translate or recite a word or letter I haven't learned yet at this stage in Duo.